The present invention relates to a method and an apparatus for automatically packing goods and, more particularly, to a method and an apparatus for automatically packing goods such as vegetables, cucumbers, tomatoes and egg-plants, for example, whether on not they are placed on a plastic tray; fruits, apples and grapes, for example, whether or not they are placed on a plastic tray; and fresh meat and the like whether or not it is placed on a plastic tray, which goods are fed continuously in a direction in series spaced a predetermined distance from each other on a conveyor, by means of a continuously fed strip of a stretch film having self-adhering and resiliently stretchable natures so as to form separate packs of goods wrapped by the strip section of the stretch film.
Recently, a method and an apparatus for wrapping vegetables, cucumbers, tomatoes and egg-plants, for example, fruits, apples and grapes, for example, and fresh meat and the like, which are placed on plastic trays, by means of a plastic film have been developed.
Heretofore used packing films are mainly of polycellophane polypropylene, nylon, vinylidene chloride and the like most of which are of gas impermeable nature, so that hermetically sealed packs are produced by these films.
Shrink packs have also been developed in which plastic films such as vinyl chloride polypropylene film of thermally shrinking nature is used and the film is shrunk by applying heated air thereto after the goods is loosely wrapped by the film so that the pack is made tight. In any case, a heat sealing process must be effected in order to bond the film after a goods is wrapped by the film in which process the portions of the film to be bonded are melted and pressure is applied to the molten portions of the film. Thus, it is rendered difficult to open the pack and, in case of shrink packs, the film is cured or hardened after it is shrunk by heat so that the overall surface of the film is made stiff thereby imparting to the pack a feeling which is unpleasant to customers.
Further, when such films having gas impermeable nature are used in wrapping vegetables, fruits and fresh meat and the like, the appearance of the packs is impaired by translucent vapor developed on the inner surface of the film generated by the goods wrapped therein.
Recently, a so-called stretch film having self-adhering and resiliently stretchable natures as well as a high permeability of carbon dioxide gas has been developed for wrapping vegetables, fruits, fresh meat and the like in order to avoid the above described disadvantages of the heretofore used films.
Packing machines utilizing the above described stretch film have also been developed. However, all of the packing machines using the stretch film heretofore proposed operate in such a manner that the film is first placed stationarily and the goods to be wrapped are pressed against the film from the lower side thereof so that the upper side and the lateral sides of the goods are wrapped by the film and then the goods are lifted together with the film so as to fold the edge portions of the film extending beyond the goods back upon the bottom side thereof so that the wrapping of the goods is completed by having the edge portions of the film adhere together on the bottom side of the goods. Thus, the operation is rendered very troublesome and is necessarily made intermittently, thereby lowering the efficiency.
When packing machines designed to use previously described polycellophane film, polypropylene film and the like are used together with the stretch film, unsightly creases and folds are generated in the film after wrapping the goods, and, since the stretch film is of the self-adhering nature, the generated creases adhere with each other so that the creases are permanently retained in the film. Thus, the packing machine for use with the polycellophane film and the polypropylene film can not be satisfactorily used with the stretch film.